The arterial wall and arterial valves are complex structures. One of the major elements of these structures is the macromolecular scaffold that provides the strength and flexibility to perform the task in hand either retaining the blood in vessels against the arterial pressure or maintaining pressure via the function of coronary valves. In the last several years it has become apparent that the actual microstructure and composition of these macromolecules could influence the progress of different disease states most notably atherosclerosis and value calcification. To gain a better understanding of this process, we have embarked on studies to understand the fine structure of the macromolecules in arterial vascular bed using a novel optical imaging technique that relies on the non-linear excitation (NLE) of collagen and elastin to provide sub-micron images of their structure in unfixed fresh samples together with direct measures oflow density lipoprotein particles (LDL) binding using fluorescence microscopy and conventional histology methods. Over the last year we have made the following progress: 1) We have developed the binding assay for LDL for macromolecular consitutents in the aortic valve of the pig heart. This was accomplished using a human LDL affinity column and applying the macromolecule homogenates directly on the column. Using high ionic strength to remove the associated macromolecules we have found that the macromolecule Decorin is the dominate agent binding to LDL. We confirmed this observation using gel electrophoresis and mass spectroscopy techniques.Purified Decorin was also found to highly associate with human LDL. 2) Active and specific fluorescent antibodies for Decorin have been developed for the histological correlation of Decorin with LDL binding in arterial walls. 3) Screening of molecules to interact with the Decorin-LDL interaction have begun. These may provide a new therapuetic approach to the treatment of atherosclerosis at is earlies stage.